Liquid Discharge Head Circulation Flow Velocity Control
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Solution Overview
Problem
Liquid discharge heads face issues with liquid thickening near discharge orifices due to evaporation, leading to poor droplet discharge speed and accuracy, especially with high solid concentrations and temperature, causing asymmetric bubbling and increased flow resistance.
Innovation Solution
A liquid discharge head with a substrate and discharge orifice forming member, featuring a pressure chamber and liquid channels with differential pressure to maintain a circulation flow velocity of 3 to 140 mm/s, suppressing liquid thickening and asymmetric bubbling by ensuring ink circulation and recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If liquid is circulated at high flow velocity to prevent thickening, then liquid thickening is suppressed, but asymmetric bubbling occurs and discharge direction accuracy deteriorates
Solution Approach 1:
The patent optimizes the circulation flow velocity to a specific range (3-140 mm/s) to balance two opposing requirements: preventing liquid thickening while avoiding asymmetric bubbling. This parameter optimization resolves the contradiction by finding the optimal velocity window where both liquid uniformity and discharge direction accuracy are maintained.
2Speed
If circulation flow velocity is increased to suppress liquid thickening, then droplet discharge speed is maintained, but flow resistance increases
Solution Approach 1:
The patent establishes an optimal circulation flow velocity range (3-140 mm/s) that balances droplet discharge speed maintenance with flow resistance control. By optimizing this parameter, the system achieves sufficient liquid circulation to prevent thickening while avoiding excessive flow resistance that would hinder droplet ejection.
3Reliability
If liquid circulation is implemented to prevent clogging, then discharge reliability is improved, but device complexity increases
Solution Approach 1:
The patent integrates the liquid circulation function directly into the existing channel structure between the discharge orifice forming member and substrate. By merging the circulation channels with the existing liquid passage structure, the patent achieves reliable liquid circulation to prevent clogging while minimizing additional device complexity.
4Manufacturing precision
If high solid concentration liquid is used to improve ink quality, then image quality is enhanced, but liquid thickening occurs more readily
Solution Approach 1:
The patent implements continuous liquid circulation through the pressure chamber at optimized velocities to continuously mix and refresh the high solid concentration liquid. This continuous action prevents local concentration gradients and thickening, allowing the use of high solid concentration ink while maintaining liquid uniformity and preventing clogging.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces liquid thickening and maintains droplet discharge direction accuracy, enhancing the overall performance and image quality of the liquid discharge head.
Implementation Method 1
a recording element configured to generate thermal energy used to discharge liquid
Implementation Method 2
Pressure at an inlet portion of the liquid supply channel is higher than pressure at an outlet portion of the liquid recovery channel
Implementation Method 3
the liquid may become concentrated and thicken near discharge orifices, due to volatile component in the liquid being discharged from the discharge orifices evaporating
Data Source
AI summary
A liquid discharge head includes: a substrate, where a recording element is disposed; and a discharge orifice forming member, where a discharge orifice, facing the recording element, and configured to discharge the liquid, is formed. The liquid discharge head has a pressure chamber, a first liquid channel configured to supply liquid to the pressure chamber, and a second liquid channel configured to recover liquid from the pressure chamber. The substrate has a liquid supply channel connected to the first liquid channel to supply liquid to the first liquid channel, and a liquid recovery channel connected to the second liquid channel, to recover liquid from the second liquid channel. Pressure at an inlet portion of the liquid supply channel is higher than pressure at an outlet portion of the liquid recovery channel, and a flow velocity of liquid within the pressure chamber is 3 to 140 mm/s.